Update posthog URL to posthog.element.io

[laurencegill]

The posthog ingress is no longer posthog.hss.element.io, and, although it is running in parallel it will be removed in the future.

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: -0.15 :warning:

Comparison is base (9c8a8cf) 12.36% compared to head (f27304b) 12.21%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #7620 +/- ## =========================================== - Coverage 12.36% 12.21% -0.15% =========================================== Files 1648 1648 Lines 163667 163667 Branches 67211 67195 -16 =========================================== - Hits 20239 19996 -243 - Misses 142763 143026 +263 + Partials 665 645 -20 ``` | Flag | Coverage Δ | | |---|---|---| | uitests | `55.05% <ø> (ø)` | | | unittests | `6.06% <ø> (-0.15%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/vector-im/element-ios/pull/7620?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im) | Coverage Δ | | |---|---|---| | [Config/BuildSettings.swift](https://app.codecov.io/gh/vector-im/element-ios/pull/7620?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im#diff-Q29uZmlnL0J1aWxkU2V0dGluZ3Muc3dpZnQ=) | `43.07% <ø> (ø)` | | ... and [14 files with indirect coverage changes](https://app.codecov.io/gh/vector-im/element-ios/pull/7620/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im)

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